C++ 如何从 QGraphicsScene/QGraphicsView 创建图像文件？
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How to create image file from QGraphicsScene/QGraphicsView?
提问by Donotalo
Given a QGraphicsScene, or QGraphicsView, is it possible to create an image file (preferably PNG or JPG)? If yes, how?
给定QGraphicsScene或QGraphicsView，是否可以创建图像文件（最好是 PNG 或 JPG）？如果是，如何？
回答by Petrucio
After just dealing with this problem, there's enough improvement here to warrant a new answer:
在刚刚处理这个问题之后，这里有足够的改进来保证一个新的答案：
scene->clearSelection(); // Selections would also render to the file
scene->setSceneRect(scene->itemsBoundingRect()); // Re-shrink the scene to it's bounding contents
QImage image(scene->sceneRect().size().toSize(), QImage::Format_ARGB32); // Create the image with the exact size of the shrunk scene
image.fill(Qt::transparent); // Start all pixels transparent
QPainter painter(&image);
scene->render(&painter);
image.save("file_name.png");
回答by jordenysp
I have not tried this, but this is the idea of how to do it.
我还没有尝试过，但这是如何做到这一点的想法。
You can do this in several ways One form is as follows:
您可以通过多种方式执行此操作 一种形式如下：
QGraphicsView* view = new QGraphicsView(scene,this);
QString fileName = "file_name.png";
QPixmap pixMap = view->grab(view->sceneRect().toRect());
pixMap.save(fileName);
//Uses QWidget::grab function to create a pixmap and paints the QGraphicsView inside it.
The other is to use the render function QGraphicsScene::render():
另一种是使用渲染函数QGraphicsScene::render()：
QImage image(fn);
QPainter painter(&image);
painter.setRenderHint(QPainter::Antialiasing);
scene.render(&painter);
image.save("file_name.png")
回答by amdev
grabWidget is deprecated, use grab. And you can use a QFileDialog
不推荐使用grabWidget，使用grab。你可以使用 QFileDialog
QString fileName= QFileDialog::getSaveFileName(this, "Save image", QCoreApplication::applicationDirPath(), "BMP Files (*.bmp);;JPEG (*.JPEG);;PNG (*.png)" );
if (!fileName.isNull())
{
QPixmap pixMap = this->ui->graphicsView->grab();
pixMap.save(fileName);
}
